1. Field of the Invention
The present invention relates to an irrigation/aspiration apparatus which supplies an irrigation fluid to a surgical site and aspirates the irrigation fluid therefrom with residual tissue. More specifically, the present invention relates to a mechanism which is advantageous to damp out or absorb pulsations caused by a peristaltic suction pump.
2. Description of Related Art
One conventionally known irrigation/aspiration apparatus supplies an irrigation fluid through an irrigation tube into a surgical site and removes the irrigation fluid and residual tissue therefrom by suction. In the field of ophthalmology, this kind of apparatus is used, for example, in cataract surgery, vitreous surgery and the like. The apparatus is generally provided with a peristaltic pump as a pump for effecting suction of the residual tissue. The peristaltic pump, however, causes pulsations which result in the disadvantage that the suction pressure varies.
One known arrangement to address the above disadvantage is, as shown in FIG. 7, to provide an air chamber in which air is sealed in the vicinity of the peristaltic pump. The air sealed in the air chamber expands and contracts in response to change in the suction pressure, thereby to accomplish rising and falling movements of a fluid level. As a consequence, the pulsations are dammed out and controlled.
With such a configuration, however, when the suction pressure through the aspiration tube becomes high (becomes more negative), the air in the air chamber may leak into the aspiration tube, which raises a possibility of change in the amount of the air. This presents a problem that the pulsation damping may not be constant. In addition, the unlimited expansion and contraction in response to the suction pressure presents another problem that rising of the suction pressure (response to the suction) may be slow.